Wyniki wyszukiwania - BazTech

1

Metody nieniszczące w ocenie rozwoju uszkodzenia materiałów konstrukcyjnych w warunkach obciążeń eksploatacyjnych

Kukla Dominik

IPPT Reports on Fundamental Technological Research

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2023

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nr 1

1--168

PL

Praca dotyczy wykorzystania metody prądów wirowych oraz innych metod nieniszczących do identyfikacji lokalnych zmian w strukturze materiału związanych z rozwojem uszkodzenia w warunkach obciążenia zmęczeniowego. Dla wybranych, metalicznych materiałów konstrukcyjnych (stale, stopy niklu i aluminium) poddanych cyklicznym obciążeniom zmiennym opracowano ilościowe charakterystyki rozwoju uszkodzenia na podstawie wyznaczonych zmian składowych odkształcenia w kolejnych cyklach obciążenia. Równocześnie z próbami zmęczeniowymi przetestowano szereg diagnostycznych metod nieniszcząych w celu oceny możliwości lokalizacji procesu inicjowania uszkodzenia zmęczeniowego w materiale próbek. Opracowane procedury badawcze z zastosowaniem metody prądów wirowych, wspierane technikami optycznymi (lub innymi technikami NDT), umożliwiły nie tylko identyfikację obszarów uszkodzenia zmęczeniowego we wczesnym etapie rozwoju, związanego ze zmianami strukturalnymi, ale także na monitorowanie procesu degradacji próbek, aż do ich zerwania. Badania przeprowadzono na stopach konstrukcyjnych dobranych nie tylko z uwagi na właściwości elektromagnetyczne, ale przede wszystkim na mechanizmy rozwoju uszkodzenia zmęczeniowego. Badania próbek z żarowytrzymałej stali 1.4903 obejmowały testy zmęczeniowe wraz z wyznaczeniem odkształceniowego współczynnika uszkodzenia zmęczeniowego (φ) opisującego dynamikę zmian składowych odkształcenia w kolejnych cyklach obciążeń zmiennych. Wyniki tych obliczeń skorelowano z wynikami pomiarów parametru sygnału prądowirowego w postaci kąta fazowego krzywej impedancyjnej, realizowanych według opracowanej procedury. Pomiar ten wykonano w zdefiniowanych miejscach na próbce poddanej obciążeniom zmiennym, po ustalonej liczbie cykli zmęczeniowych. Przeprowadzono także badania mikrostrukturalne w zakresie metalografii (zgładów poprzecznych i podłużnych) oraz fraktografii (przełomów) próbek poddanych próbom zmęczeniowym. Badania mikrostrukturalne potwierdziły występowanie zjawisk związanych z degradacją zmęczeniową, które mogą uzasadniać zmiany charakterystyki sygnału prądowirowego w funkcji jej rozwoju. Zjawiska te to przede wszystkim lokalne odkształcenia plastyczne wokół twardych wtrąceń oraz mikropęknięcia. Badania zmęczeniowe dla stali 1.4903 przeprowadzono na próbkach w stanie dostawy oraz na próbkach eksploatowanych w warunkach pracy rurociągów pary świeżej w jednej z krajowych elektrowni. Na podstawie analizy uzyskanych wyników badań i ich obróbki opracowano metodykę oceny rozwoju degradacji wyrażonej ilościowo poprzez narastanie składowych odkształcenia niesprężystego w kolejnych cyklach obciążenia. Na podstawie opracowanych procedur pomiarowych uzyskano wyniki wskazujące zarówno na możliwość lokalizacji i identyfikacji defektów powstałych wskutek procesu zmęczeniowego we wczesnym etapie jego rozwoju, jak i na ilościową ocenę stopnia degradacji na podstawie analizy zmian parametrów wyznaczonych techniką prądów wirowych w kolejnych cyklach obciążeń zmęczeniowych. Kolejne wyniki uzyskano w badaniach stopu niklu MAR 247 stosowanego do budowy łopatek turbin silników lotniczych. Serię próbek z tego stopu poddano próbom zmęczeniowym, którym towarzyszyły badania nieniszczące z wykorzystaniem technik optycznych, takich jak cyfrowa korelacja obrazu (DIC - Digital Image Correlation) czy elektroniczna interferometria plamkowa (ESPI - Electronic Speckle Pattem Interferometry). Na próbkach poddawanych testom zmęczeniowym przeprowadzono także pomiary konduktywności z zastosowaniem metody prądów wirowych (według opracowanej procedury) oraz klasyczne badania defektoskopowe. Metody optyczne pozwoliły na wczesną identyfikację lokalnych koncentracji odkształcenia, wynikających z lokalnych koncentracji naprężenia. Obszary te stanowiły miejsce rozwoju propagacji pęknięcia dominującego, co potwierdziły prowadzone równolegle badania metodą prądów wirowych, które ujawniły także inne pęknięcia zmęczeniowe na etapie poprzedzającym rozwój uszkodzenia dominującego. Ponadto wykazano lokalne zmniejszenie konduktywności w obszarze inicjowania uszkodzenia, związanego z koncentracją odkształcenia. Podobne badania wykonano dla stopu Inconel 718 z zastosowaniem próbek o zmiennej powierzchni przekroju, co umożliwiało uzyskanie zmiennego pola deformacji. Opisano także wyniki badań dotyczących identyfikacji i oceny wad technologicznych oraz eksploatacyjnych związanych m.in z lokalnym przegrzaniem struktury materiału przez narzędzie szlifierskie, niewłaściwie przeprowadzoną obróbkę plastyczną na zimno oraz z oddziaływaniem atmosfery wodorowej. Opracowane procedury badawcze dają możliwość identyfikacji defektów związanych z przypaleniami szlifierskimi, a wykonując analizę parametrów rejestrowanego sygnału impedancji uzyskanego metodą prądów wirowych, można poznać ich właściwości. Dotyczy to ilościowej oceny głębokości strefy przegrzania oraz jakościowej oceny zmian twardości warstwy spowodowanej oddziaływaaniem wysokiej temperatury.

EN

The work concerns the application of eddy current and other non-destructive methods for identification of local changes in the structure of material due to the development of damage under fatigue conditions. For selected, metallic structural engineering materials (steels, nickel and aluminum alloys) subjected to cyclic alternating loads, the quantitative characteristics of damage development were presented and described on the basis of the evolution of deformation components in subsequent load cycles. Along with the fatigue tests, a number of nondestructive diagnostic methods were used to assess the possibility of locating the fatigue failure initiation process in various materials. The proposed research procedures of the eddy current method, supported by optical techniques, allowed not only for early-stage identification of fatigue damage development areas but also to monitor the degradation process of specimens, up to their failure. The eddy current measurements were carried out on alloys selected on the basis of their (magnetic) properties and mechanisms of fatigue damage development. The tests of the heat-resistant steel specimens (1.4903) included fatigue tests with the determination of the deformation fatigue damage factor describing the dynamics of changes in the deformation components in subsequent load cycles. The results of these calculations were correlated with the measurements of the eddy current signal phase angle, carried out according to the developed procedure. This measurement was performed in selected areas on a specimen subjected to variable loads and after a predetermined number of fatigue cycles. Microstructural observations of specimens subjected to fatigue tests were also carried out in the field of metallography (transverse and longitudinal sections) as well as fractography (fractures). Microstructural studies allowed to confirm the occurrence of processes and phenomena related to fatigue degradation, which may justify changes in the values of the eddy current signal parameters (phase angle) as a function of its development. These were mainly local plastic deformations around hard inclusions and microcracks. Fatigue tests for this steel were carried out on specimens in the as-received condition and on the live steam pipelines operated in the power plant. Based on the eddy current analysis, a fatigue life determination methodology was developed. Such methodology considers the development of degradation, expressed quantitatively, through the growth of the deformation components in subsequent cycles. Based on the established measurement procedures, the obtained results indicate the possibility of localization and identification of fatigue damage at an early stage of its development, as well as a quantitative assessment of the degree of degradation based on the eddy current technique. Further investigations were performed on the MAR 247 nickel alloy used in the construction of turbine blades of aircraft engines. A series of specimens were subjected to fatigue tests and simultaneously monitored by non-destructive, optical testing techniques such as Digital Image Correlation (DIC) and Electronic Speckle Pattern Interferometry (ESPI). Subsequent conductivity measurements were performed on such specimens by using the eddy current method (according to the developed procedure), as well as classic defectoscopy tests. Optical techniques enabled an early identification of local strain concentrations resulting from local stress concentrations. In these areas, the development of the dominant crack propagation was observed. Such observations were further confirmed by the parallel eddy current tests, which also revealed other fatigue cracks at the stage preceding the development of the dominant damage. A local drop in the conductivity value in the area of damage initiation was also found in the form of strain concentration. Similar tests were also carried out for the Inconel 718 alloy by using specimens with a variable cross-sectional area enabling to obtain a variable deformation field. Additionally, an attempt to identify technological defects resulting from local overheating of the material structure by the grinding tool was made. The developed test procedures enabled the detection of defects related to grinding burns. The subsequent analysis of the parameters of the recorded impedance signal obtained by the eddy current method, allows the quantitative assessment of the depth of the overheating zone and the qualitative assessment of changes in the hardness of the layer, resulting from the effect of high temperature.

2

Obręcze - przykłady rozwiązywania

Janik Maciej

Konstrukcje Stalowe

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2022

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nr 2

14--19

3

Thermal-strength analysis of a slow closing valve during accelerated startup of a steam turbine

Bryk Mateusz

Journal of Power Technologies

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2022

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Vol. 102, nr 2

68--78

EN

This study assesses the accelerated startup of a steam turbine from the perspective of a slow closing valve. Valves are one of the first components affected by high temperature gradients and are key components on which the power, efficiency and safety of the steam system depends. The authors calibrated the valve model based on experimental data and then performed extended Thermal-FSI analyses relative to the experiment. Key results of the work include the possibility to reduce the startup time of a steam turbine while complying with stress limits and not excessively straining structural components of the valve. The single most important finding is that there is no need to change valves when accelerating the startup of steam turbines.

4

Badania porównawcze odporności na zginanie i energochłonnności profili ceowych zamkniętych i specjalnych

Gardyński Leszek

Dozór Techniczny

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2021

|

z. 3

20--24

PL

W artykule opisano wyniki badań doświadczalnych wytrzymałości na zganianie pod względem energochłonności profili stalowych: ceownika 80 mm, kwadratu uzyskanego z połączenia dwóch takich ceowników oraz specjalnego profilu Sigma – Σ, stosowanego do ochronnych barier drogowych. Inspiracją był wypadek drogowy, podczas którego samochód osobowy uderzył w barierę ochronną z prędkości powyżej 100 km/h pod stosunkowo dużym kątem.

5

Investigation of the correlation between crack propagation process and the peak strength for the specimen containing a single pre-existing flaw made of rock-like material

Yang Hengtao, Lin Hang, Wang Yixian, Cao Rihong, Li Jiangteng, Zhao Yanlin

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 2

458--478

EN

This paper investigated the relationship between the strength of fractured rock and the crack propagation process. A series of uniaxial compression tests were carried out on the rock-like material specimens with single pre-fabricated flaw. Moreover, DIC (digital image correlation) technology was utilized to monitor and analyze the failure process of specimens. The initiation of each crack was defined as a key event, and the relationship between several key events and the axial load of the specimen during the crack propagation was quantitatively analyzed. The time-sequence analysis of crack propagation was also conducted by selecting benchmark points on the both sides of major cracks. It can be found that only the wing crack propagation occurs and there is no obvious shear crack before the peak strength. When the first secondary crack initiated, the specimen reached its peak strength and the wing crack just reached its critical length. Beyond the peak strength, secondary cracks initiated and coalesced rapidly, which leads to the sudden failure of fractured rock. Therefore, the peak strength of the specimen can be assessed by taking the critical length of the steadily propagating wing crack as the condition which determines whether the specimen reaches the peak strength. Furthermore, the discrete element numerical simulation was also implemented to confirm the experimental results.

6

Analytical and experimental study on micro-grinding surface-generated mechanism of DD5 single-crystal superalloy using micro-diamond pencil grinding tool

Sun Yao, Su Zhipeng, Gong Yadong, Ba Dsechun, Yin Guoqiang, Zhang Huan, Zhou Linhu

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 1

353--374

EN

Single-crystal superalloy is characterized by no grain boundary and widely used in the aviation and aerospace industry due to its high creep strength and high thermal fatigue resistance, especially applications in aero engine necessitate numerous micro-scale structures made of single-crystal superalloy material with high-dimensional accuracy and surface quality. Micro-grinding as one of micro-precision machining technology is capable to fabricate micro-parts and structures with high machining precision and quality. In this work, a series of diamond micro-pencil grinding tool (MPGT) with diameter ranged from about 100 to 800 μm are firstly prepared by hybrid processes. The surface-generated mechanism of micro-grinding process associated with effects of length ratio of rubbing, ploughing and chip forming were explored based on analytical and experimental investigations. In addition, a novel analytical force model for the DD5 material machined by MPGT is developed considering variable size effect under different length proportion, protrusion height distribution of MPGT and material mechanical properties, which can more accurately agree well with the measured results compared with the traditional micro-grinding force model. This study enabled an in-depth understanding of mechanical behaviour characteristics, surface formation and material removal mechanism under microscopic scale of single-crystal superalloy involved in micro-grinding.

7

Safety of construction components in a very high number of load cycles

Nový František, Belan Juraj, Bokůvka Otakar

System Safety : Human - Technical Facility - Environment

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2020

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Vol. 2, nr 1

199--206

EN

Progressive, high-strength materials have an important position in the transport industry. In this industry, components are subject to high safety and reliability requirements because they often operate under long-term cyclic stress regimes. The paper presents results of fatigue resistance of high-strength materials such DOMEX 700MC, HARDOX 400, HARDOX 450, and INCONEL 718 (UTS from 850 to 1560 MPa) measured at high-frequency cyclic loading (f = 20 kHz, T = 20 ± 5 ° C, push-pull loading, cycle asymmetry parameter of R = -1) in the area from N = 2x106 to N = 2x108 cycles. Fatigue resistance showed a continuous decrease about average value Sa2x108/Sa2x106 = 19.1%.

8

Praktyczne badania utraty udarności polipropylenu w niskich temperaturach

Gardyński Leszek

Dozór Techniczny

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2020

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z. 3

22--24

PL

W artykule opisano wyniki badań doświadczalnych odporności na obciążenia dynamiczne pojemników z polipropylenu w obniżonych temperaturach. Głównym wnioskiem jest to, że przy ujemnych temperaturach badane tworzywo jest znacznie bardziej podatne na uszkodzenia dynamiczne. Należy o tym pamiętać przy transporcie produktów w opakowaniach wykonanych z tego materiału.

9

Influence analysis of the main types of defects and damages on bearing capacity in reinforced concrete elements and their research methods

Lobodanov Мaksym, Vegera Pavlo, Blikharskyy Zinoviy

Production Engineering Archives

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2019

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Vol. 22

24--29

EN

In current economic trends, changes in construction using are required. It usually leads to changes in value and type of the working load on building structures, with the requirement to rate the technical state and replace or strengthen the elements. An important aspect of determining the residual bearing capacity of damaged bending reinforced concrete elements is the research concerning the influence of difference defects and damages on the change of strength and deformability. In the article main types of damages and defects, methods of studies of damaged reinforced concrete elements and the expediency of usage of this elements are described. However, most methods are suitable only for certain defects and damages due to the large complexity of calculations and the consideration of multifactoriality. Significant complexity of a single method for calculating damaged elements depends on the possible changing stress strain state of an element in combination with certain defects and damages, the presence of a non-complete separation where during loading or alteration of the damaged element the fractions become included in the work, reinforced concrete is the composite material which carrying complexity in calculating the joint work of its components.

10

Strength statistical characteristics of the isotropic materials with disc-shaped defects

Kvit R.

Journal of Applied Mathematics and Computational Mechanics

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2018

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Vol. 17, nr 4

25--34

EN

The expressions of the probabilities density distribution of failure loading for an elastic isotropic body under the action of a homogeneous axisymmetric loading are written. The disc-shaped cracks that do not interact with each other are uniformly distributed. The correlation for finding the most probable, mean value, dispersion and variation coefficient of failure loading are obtained. The dependence of the mentioned statistical strength characteristics on the type of applied loading, number of defects (body sizes) and structure material heterogeneity are investigated.

11

Odporność na przebicia materiałów kompozytowych

Kyzioł L.

Autobusy : technika, eksploatacja, systemy transportowe

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2018

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R. 19, nr 6

540--543, CD

PL

Konstrukcjom, które przenoszą obciążenia dynamiczne i których odporność decyduje o życiu i bezpieczeństwie człowieka stawia się szczególne wymagania. Wymagania dotyczą zarówno sfery materiałowej jak i konstrukcyjnej. To z kolei zmusza do poszukiwania optymalnych metod obliczeniowych, z uwzględnieniem nieliniowości, tak geometrycznej jak i fizycznej, wynikającej z konfiguracji struktury konstrukcji. Przykładem są różne konstrukcje balistyczne (osłony balistyczne), które są uderzane pociskami w których skumulowana jest ogromna energia. W takim przypadku uderzenie w tarczę (osłonę) pociskiem można rozpatrywać jako obciążenie spowodowane uderzeniem masą. Matematycznie zjawiska obciążeń przy dużych szybkościach odkształceń opisuje się różnymi modelami. Aparat matematyczny jest dość złożony ponieważ wymagana jest duża liczba „współczynników”, ponadto uzyskane wyniki badań nie zawsze są powtarzalne i ma na to wpływ wiele czynników. W pracy zaprezentowano wyniki przestrzeliwania tarcz wielowarstwowych z materiałów kompozytowych pociskami kalibru 7,62 mm. Tarcza składała się z trzech warstw, warstwy zewnętrzne stanowiły okładziny stalowe lub aluminiowe, warstwę wewnętrzną stanowiło drewno naturalne lub modyfikowane. Próbki w kształcie tarcz były o średnicy 50 mm i różnej grubości. Wyniki badań pozwoliły ocenić wpływ modyfikacji drewna na jego odporność na przebicia.

EN

For structures that carry dynamic loads, the requirements are imposed for safety reasons. The requirements apply to both materials and construction. This requires searching for optimal calculation methods, including geometric and physical nonlinearity, which are results from the construction of the structure. An example is various ballistic structures (ballistic shields), which are hit by bullets in which huge energy is accumulated. In this case, the hitting in the shield with a bullet can be considered as a load due to mass impact. Loads at high strain rates are described by various mathematical models. The mathematical model is complex because a large number of "coefficients" is required, moreover, the obtained test results are not always repeatable. The paper presents the results of shooting multilayer plates with composite materials with 7.62 mm caliber bullets. The shield consisted of three layers, the outer layers were steel or aluminum, the inner layer was natural or modified wood. The samples had the shape of a shield and were 50 mm in diameter and of different thickness. The results of the research allowed to assess the impact of wood modification on its puncture resistance.

12

Failure characteristics of jointed rock-like material containing multi-joints under a compressive-shear test: Experimental and numerical analyses

Cao R. H., Cao P., Lin H., Ma G. W., Zhang C. Y., Jiang C.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 3

784--798

EN

Extensive efforts have been made to gain a better understanding of the failure behaviour of rocks and rock-like materials, but crack propagation and failure processes under compressive-shear loading have not yet been comprehensively investigated. To address this area of research, the peak shear strengths (τ) and failure processes of specimens with multiple joints are studied by lab testing and particle flow code (PFC2D). Four types of failure modes are observed: (a) shear failure through a plane (Mode-I), (b) intact shear failure (Mode-II), (c) oblique shear crack connection failure (Mode-III), and (d) stepped path failure (Mode-IV). The failure mode gradually transformed to Mode-III as α (joint inclination angle) increases from 0° to 90° in the specimens. In addition, with increasing joint distance (d) in the specimens, the failure mode changes to Mode-II. As the non-overlapping length between joints (c) in the specimens increases, the failure mode changes to Mode-IV. The joint geometry has a major influence on the shear strength of the jointed specimens. The peak shear strength of specimens with different joint inclination angles is obtained when α = 45°. Additionally, the peak shear strength increases as the joint distance (d) and non-overlapping length (c) increase.

13

Experimental study on uniaxial mechanical properties and crack propagation in sandstone containing a single oval cavity

Huang Y. H., Yang S. Q., Hall M. R., Tian W. L., Yin P. F.

Archives of Civil and Mechanical Engineering

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2018

|

Vol. 18, no. 4

1359--1373

EN

The geometry and orientation of cavities in a rock mass has a significant influence on the failure mechanism and fracture propagation. The theoretical study of these behaviors is of great importance to enable fundamental understanding of unstable failure in rock mechanics. A very limited number of experimental studies have been conducted for sandstone specimens containing oval cavities. Sensitive parameters include the short axis (b) to long axis (a) ratio. Here, we enhance the present understanding of crack coalescence behavior around an oval cavity by applying uniaxial compression tests to sandstone cores containing manually inserted single oval cavity, combined with photographic and acoustic emission monitoring. The b:a ratio was varied from 1/4 to 1/1, thus the cross-sectional cavity shape evolved from oval to a fully circular opening. The experimental results showed that the stress–strain curves of specimens containing cavities exhibited multiple stress reductions prior to peak strength, which led to a sudden increase in the accumulated AE count-rate. As the b:a ratio was increased, the uniaxial compressive strength, crack initiation stress and peak strain of cavity specimens all decreased linearly. Tensile fractures, shear fractures, and compound shear-tensile fractures were all observed to emanate from the cavities. Compared to the intact specimen, the failure mode of cavity specimens comprised a mixture of tensile and shear cracks, emanating from the tips (or surfaces) of the oval cavity. For specimen with a cavity angle of 45°, when the b:a ratio was below 1/2, no tensile crack from the surface of short axis was initiated, whereas tensile crack was observed clearly after b:a = 1/2. This study not only increases our understanding of mechanical failure behavior in fractured rock, but also enhances our knowledge of underground tunneling or roadway stability.

14

Experimental study of Portevin–Le Châtelier bands on tensile and plane strain tensile tests

Sene N. A., Balland P., Bouabdallah K.

Archives of Civil and Mechanical Engineering

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2018

|

Vol. 18, no. 1

94--102

EN

The aim of this article is to show that it is possible to create an experimental database to better model Portevin–Le Châtelier (PLC) phenomenon with two kinds of solicitation. Indeed, two kinds of specimen are tested: conventional tensile specimens and specimens designed for plane strain tensile test. In order to better understand this phenomenon and above all to put away any geometry effect, two materials are tested: one without PLC bands (AU4G) that is used as reference and AlMg3 which is well known for its PLC bands. The image correlation tool is used to analyse the creation and the spread of PLC bands. Characteristic parameters of the bands are then measured: width, angle, transported strain, strain rate, and velocity. The originality of this paper is first to show that PLC bands are present during plane strain tensile test and then to characterize the bands thanks to image correlation. These experimental databases could be very useful for those who develop models on PLC phenomenon.

15

Analysis of the mechanical properties and of micrographs of refill friction stir spot welded 7075-T6 aluminium sheets

Kubit A., Kluz R., Trzepieciński T., Wydrzyński D., Bochnowski W.

Archives of Civil and Mechanical Engineering

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2018

|

Vol. 18, no. 1

235--244

EN

The main aim of the investigations was to determine the significance of parameters of RFSSW for the strength parameters of the resulting joint. RFSSW joints were made in 0.8-mm-thick 7075-T6 aluminium alloy using different welding parameters (tool rotational speed v, tool plunge depth, and joining time). The load capacity of joints was determined by shear tests. The optimum welding parameters which assure the highest load capacity (4.09 kN) in the tensile/shear test are: tool rotational speed of 3000 rpm, tool plunge depth of 1.55 mm, and joining time of 1.25 s. In the conditions of the static tensile test under pure shear the highest joint capacity (6.48 kN) is found for the joint welded at a tool plunge depth of 1.7 mm. Depending on the tool plunge depth, three types of joint damage were observed during tensile/shear tests: plug type fracture, shear fracture, and plug-shearracture. Incomplete refill is the main weld defect observed which is located on the path along which the sleeve plunges into the sheet. It was also found that alclad between the upper and lower sheets worsens the joint quality between the stir zone and thermo-mechanically affected zone.

16

Assessment of compressive strength and compressive modulus parallel to the grain of oak and tauari wood after thermo-mechanical modification

Laskowska A.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2018

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No. 103

70--76

EN

European oak and tauari wood were subjected to thermomechanical modification. One treatment cycle consisted of three stages: heating the wood in a hydraulic press; wood densification; and cooling the wood samples in unheated hydraulic press without exerting pressure. The treatment temperature was 100 °C or 150 °C. The modification temperature significantly affected the compressive strength parallel to the grain of oak and tauari wood. Such dependencies were not found in the case of compressive modulus of elasticity parallel to the grain of tested wood species. The compressive strength of tauari wood modified at 100 oC and 150 oC was, respectively, 16% and 20% greater than the compressive strength of oak wood modified at the same temperatures. The compressive strength parallel to the grain of the oak and tauari wood depended linearly on wood density and load.

PL

Drewno dębu i tauari poddano obróbce termo-mechanicznej. W pierwszym etapie drewno ogrzewano kontaktowo w prasie hydraulicznej, następnie zagęszczano, po czym poddawano chłodzeniu w nieogrzewanej prasie hydraulicznej bez użycia ciśnienia. Temperatura półek prasy, przy której prowadzono proces zagęszczania drewna wynosiła 100°C lub 150°C. Temperatura obróbki wykazała istotny wpływ na wytrzymałość na ściskanie wzdłuż włókien drewna dębu i tauari. Zależności tych nie stwierdzono w przypadku modułu przy ściskaniu wzdłuż włókien badanych gatunków drewna. Wytrzymałość na ściskanie drewna tauari zagęszczanego w temperaturze 100°C i 150°C była odpowiednio o 16% i 20% wyższa niż wytrzymałość na ściskanie drewna dębu modyfikowanego w tych samych temperaturach. Wytrzymałość na ściskanie wzdłuż włókien drewna dębu i tauari zależała liniowo od gęstości drewna i obciążenia wywieranego na próbkę.

17

Analysis of strength characteristics of composite materials under vibration loads at higher temperatures

Sołek K., Kalisz D., Arustamian A., Ishchenko A. A.

Journal of Machine Construction and Maintenance - Problemy Eksploatacji

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2017

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no. 1

93--97

EN

This paper focuses on the analysis of mechanical properties of organic-inorganic polymeric hybrid material Multimetall “Stahl 1080” containing metallic particles. This material is designed for the regeneration of used metallic parts made of steel, cast iron, or composite materials. This type of material provides a 100% contact with the surface of the filled material, attenuation of vibration loads during the operation under strains, as well as protection against corrosion and tribological wear. The analysis concentrated on the behaviour of the material under vibration loads at higher temperatures.

PL

W artykule zaprezentowano analizę właściwości mechanicznych materiału hybrydowego polimerowego organiczno-nieorganicznego Multimetall “Stahl 1080” zawierającego cząstki metaliczne. Materiał ten został zaprojektowany w celu regeneracji zużytych metalicznych części ze stali, żeliwa lub materiałów kompozytowych. Ten typ materiału zapewnia 100% przyleganie do powierzchni pokrywanego materiału, tłumi drgania, jak również chroni przed korozją i zużyciem tribologicznym. Analizę skoncentrowano na badaniu oddziaływania na materiał drgań w wysokich temperaturach.

18

Mathematical modeling of mechanical phenomena in the gantry crane beam

Sowa L., Kwiatoń P.

Journal of Applied Mathematics and Computational Mechanics

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2017

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Vol. 16, nr 3

97--104

EN

This work concerns the numerical analysis of the gantry crane beam in the context of the safety of the structure. The mathematical model and numerical simulations of mechanical phenomena in the gantry crane beam are presented in this paper. The analysed gantry crane beam has a T-section. As a result of the computations carried out, the stresses and displacements of the gantry structure were obtained. The influence of the value and loading force position on the equivalent stress in the gantry crane beam was evaluated. It was sought that the maximum value of Huber-Mises-Hencky stress induced in the beam was less than the strength of material, so the design is safe.

19

Simulating progressive damage of notched composite laminates with various lamination schemes

Mandal B., Chakrabarti A.

International Journal of Applied Mechanics and Engineering

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2017

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Vol. 22, no. 2

333--347

EN

A three dimensional finite element based progressive damage model has been developed for the failure analysis of notched composite laminates. The material constitutive relations and the progressive damage algorithms are implemented into finite element code ABAQUS using user-defined subroutine UMAT. The existing failure criteria for the composite laminates are modified by including the failure criteria for fiber/matrix shear damage and delamination effects. The proposed numerical model is quite efficient and simple compared to other progressive damage models available in the literature. The efficiency of the present constitutive model and the computational scheme is verified by comparing the simulated results with the results available in the literature. A parametric study has been carried out to investigate the effect of change in lamination scheme on the failure behaviour of notched composite laminates.

20

Modeling of transmission gears: spur (with straight teeth) and worm, using program Inventor Professional and Simulation Mechanical: application test

Matczak J., Matczak K.

Autobusy : technika, eksploatacja, systemy transportowe

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2017

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R. 18, nr 6

952--955, CD

EN

The article presents designing of gearboxes using Inventor Professional 2017 and the ability to implement these projected models to the Simulation Mechanical 2017. For comparison there were design purposes transmission gears as: spur gear with straight teeth and worm gear. The results of calculations and parameters of the transmission gears are presented in tabular form. Shown dynamic analysis-nonlinear allowing to examine the transmission gears for endurance.

PL

W artykule przedstawiono proces projektowania przekładni przy pomocy programu Inventor Professional 2017 oraz możliwość zaimplementowania tychże modeli do programu Simulation Mechanical 2017. Dla celów porównawczych zaprojektowano przekładnie: walcową (o zębach prostych), a także przekładnię ślimakową. Wyniki obliczeń oraz parametry przekładni przedstawiono w postaci tabelarycznej. Przeprowadzono analizę dynamiczną-nieliniową pozwalającą na zbadanie przekładni pod kątem ich wytrzymałości.